This invention relates to a method for D.C. braking a three-phase asynchronous maching having three Y-connected stator windings, in which, for braking the machine, the first and the second stator winding are acted upon by direct current and, at the same time, the third stator winding is short-circuited. The invention also relates to a circuit arrangement for implementing the method.
Such a method and a corresponding circuit arrangement is described in German Pat. No. 698 812. In that patent, for braking a three-phase asynchronous motor with Y-connected stator windings, one stator winding is short-circuited and the two other stator windings are connected in series and acted upon by direct current. In this method, the direct current is disconnected by delayed switching of a relay and a constant braking time results. Thus it may happen that the direct current is switched off before the braking is complete. In the alternative, the braking may have been finished before the direct current is switched off with the result that continued flow of direct current through the two stator windings produces a power loss until the windings are disconnected.